Guidance Note 3: Inspection & Testing (Electrical Regulations)

Product Information

Appendix 4 includes minor changes concerning a cable surrounded by thermal insulation. Appendix 6 Model forms for certification and reporting To demonstrate competence, inspectors will need to have a high level of experience and knowledge of the type of installation to be inspected. They will also further demonstrate that they have undergone training and education in inspection and testing with evidence of qualification(s) from a recognised examining body. Provides clear guidance on what can be a confusing aspect of BS 7671. It is ideal for those working in specification, testing and inspection and for consulting engineers, as well as electrical installers and has been fully updated to BS 7671:2018:2022. PD IEC/TR 62350:2006 Guidance for the correct use of residual current-operated protective devices (RCDs) for household and similar use.

The IET Wiring Regulations is the national standard to which all domestic and industrial wiring must conform. It is essential to all those concerned with the design, installation and maintenance of electric wiring in buildings. The 18th Edition is a major update to this title and contains extensive changes to many areas of BS 7671. A key guide to this important area of BS 7671. It is intended for all involved with specifying, designing, installing or verifying electrical installations and has been fully updated to BS 7671:2018:2022. The technical content of this section has been extensively revised and expanded. Requirements of this section now apply to:This is where knowledge of relevant product standards is essential, it would be reasonable to expect a 40 ms maximum disconnection time for a test at five times I Δn as would be the case with an AC test. However, this is not the case as the product standard BS EN 61008 requires a half wave pulsating residual current of 0.35 A (350 mA), see Table 4 extracted from BS EN 61008-1:2012+A2:23-1:2012+A11:2015. This section includes changes to automatic disconnection of supply and additional protection. Section 717 - Mobile or transportable units Regulation 443.4 for determining if protection against transient overvoltages is needed has been redrafted. Regulation 443.4.1 now requires protection against transient overvoltages to be provided where the consequence caused by the overvoltage could result in: Regulation 514.12 (Notices: periodic inspection and testing) now contains an exception for domestic (household) premises in certain situations.

For those that decide to continue to carry out all of the tests previously required, it is important to consider what the benefits really are and if the lifespan of the RCD be reduced, possibly to the point where it may not work when required. RCD testing issuesRegardless of RCD type, e.g. AC, A, F or B, an alternating current test shall be used at the rated residual operating current (I Δn), with a maximum operating time not exceeding 300 ms for general non-delay type RCDs. It is very important to note that Regulation 621.2 requires the installation to have a “ detailed examination” and that examination is to be “ supplemented by appropriate tests”. It is essential for persons engaged in inspection and testing to understand that the inspection is more important than the testing. IET Guidance Note 3, Section 3.7, Table 3.2 provides some useful information regarding recommended initial frequencies of inspection of electrical installations. It’s important to note that these are recommendations and not legal requirements, they are intended for the initial.

Regulation, 702.414.3, concerning SELV and PELV, has been introduced. Section 703 - Rooms and cabins containing sauna heaters The description of the extent of the installation covered by the report is arguably one of the most important sections to complete as it describes what is being inspected and tested. Testing is an ancillary activity to inspection, rather than the converse. When carrying out the inspection and test, the inspector should compare the installation for conformity with the current edition of BS 7671 and record any identified non-compliances. The requirements for RCD testing have been changed and Table 3A (Time/current performance criteria for RCDs) in Appendix 3 has been deleted. Regardless of RCD Type, an alternating current test at rated residual operating current (IMn) is used to verify the effectiveness. Section 702 - Swimming pools and other basins

However, a ‘fuse box’ is unlikely to contain sufficient provisions for RCD protection where necessary and depending on the deficiencies observed, it may be more cost-effective to replace for a modern consumer unit. The requirements for testing RCDs have been simplified, a single test is all that is required to show compliance with the minimum requirement laid out in BS 7671:2018+A2:2022. Regardless of RCD type, the test is carried out using an alternating test current, applied at the RCD’s rated residual operating current I Δn, the maximum disconnection time is expected to be less than 300ms for a general non-delay type RCD. For S type time-delayed RCDs, the operating time should be 130 - 500 ms. Other kinds of RCD testing may be useful for fault finding purposes. A note has been added clarifying that where non-metallic pipes, e.g. plastic, enter the building and are then connected to metallic pipes within the building, the metallic pipes within the building do not normally require protective bonding as they are unlikely to be extraneous-conductive-parts. Reference to insulating sections has been removed.

In Step 3, line and circuit protective conductors are cross-connected, and a resistance measurement is taken between line and circuit protective conductor at each point on the ring final circuit. Step 3, resistance at Test Point 1 There seems to be some slight differences with regards to acceptable Zs values when comparing the two documents BS7671 17th Edition A3 and Guidance Note 3 Inspection and Testing 17th Edition A3. Regulation Group 643.3 has been redrafted. The requirements for testing insulation resistance where equipment is likely to influence the verification test or be damaged has been clarified and reference is made to a 250 V DC test following the connection of equipment. Questions often arise concerning the competence of persons carrying out inspection and testing. Sadly, less than scrupulous contractors will knowingly send out non-competent persons, such as apprentices, friends and inexperienced electricians, to carry out inspection and testing. Regulation 16 of the Electricity at Work Regulations 1989 requires persons carrying out electrical work to be competent. The Health and Safety Executive (HSE) also provides guidance on these regulations regarding technical knowledge and experience of working on particular systems. Predicted measured resistance = r y//r g = 0.5762×0.4264 ÷ (0.5762+0.4264) = 0.2451 Ω Step 3, resistance at Test Point 6NOTE 2: Regulation 16 of the Electricity at Work Regulations 1989 requires persons to be competent to prevent danger and injury. The HSE publication HSR25 provides guidance on this.’ When the Type A setting is selected on the instrument, a half wave pulsating residual test current superimposed on a smooth direct current of 6 mA is produced, which effectively applies a 1.4 multiplier to the rated residual current (I Δn). For example, if the 30 mA setting is selected, the RCD will be subjected to a test current of 42 mA (30 x 1.4 = 42 mA).